WGMRs are useful in photonic devices to conserve photons. WGMRs can be found in microwave receivers, high frequency receivers, parametric compact oscillators, and frequency references. WGMRs can be characterized by two partially dependent values, finesse (F) and quality factor (Q). Q is a parameter defining WGMR performance.
Prior art WGMRs achieve larger finesse values compared with other prior art resonators. For example, fused silica WGMRs with finesse values of 2.3×106 and 2.8×106 have been demonstrated. Crystalline WGMRs reveal even larger finesse values, F=6.3×106, because of low attenuation of light in the transparent optical crystals. The large values of F and Q result in the enhancement of various nonlinear processes.
The theoretical optimum values for finesse and quality factor of an optical crystalline WGMR at room temperature are 1014 and 109, respectively. Experimental results using WGMRs of the prior art, however, provide F and Q values that are a thousand times lower than the theoretical optimum. The difference between theoretical values and the experimental results are due to media imperfections. The crystalline material of the WGMR has intrinsic structural defects caused by the processing of the material for the WGMR application. These defects scatter light and therefore limit the Q and F values of the WGMR.
Accordingly, there is a need for a WGMR having improved finesse and quality factor values.